Rotor for radial turbines



Nov. l, 1949 A. BUCH! RTOR FOR RADIAL TURBINES 4 Sheets-Sheet 1 Original Filed Oct, 21, 1942 f. ufl/,

Nov. 1, 1949 A. BCHI 2,486,732

ROTOR FOR RADIAL TURBINES Original Filed Oct. 21. 1942 4 Sheets-Sheet 2 Nov. l, 1949 A. BUHl 2,486,732

ROTOR FOR RADIAL TURBINE Original Filed Oct. 21, 1942 4 Sheets-Sheet 5 Nov., E, 1949 A. BUcHl 2,486,732

ROTO FOR RADIAL TURBINES Original Filed Oct. 21, 1942 4 Sheets-Sheet 4 Wwe/2 for f Patented Nov. l, 1949 ROTOR FOR RADIAL TURBINES Alfred Bchi, Winterthur, Switzerland Continuation of application Serial No. 616,203.

September 14, 1945, which is a division of application Serial No. 462,859, October 21, 1942. This application August 15, 1 949, Serial No. 110,448. In Canada August 18, 1942 8 Claims.

This invention is a continuation of my application Serial No. 616,203 which itself was a division of my application Serial No. 462,859, now Patent No. 2,390,506, dated December 11, 1945, and relates to rotors for radial turbines particularly adapted for use with hot gaseous motive uids consisting of a disc-like rotor body presenting a plurality of blades successively spaced from each other to form the side walls of a plurality of successive passages, the said body forming bottom walls for the said passages between adjacent blades, the passages being arranged to receive gas admitted substantially radially at the outer periphery of the rotor and to direct the gas inwardly toward the axis of the rotor, the bottom walls being curved from radial to axial directions as the gas flows radially inwardly and then axially from the inlet to the outlet ends of the passages, the inlet end of the bottom wall lying in a plane substantially perpendicular to the rotor axis and the outlet end of the bottom wall extending in a direction along the rotor axis, each blade extending obliquely to the rotor axis and each side of each blade lying substantially within a single plane.

In a further embodiment of my invention, the cross sectional area of the outlet end of each passage and the inclination of the outlet ends of the blades produce relative gas velocities adjacent the base and adjacent the tip of the outlet end of each blade which are substantially equal to each other and also produce absolute gas velocities adjacent those points which are substantially equal to each other. Through these measures reciprocal inuences and disturbances of the gas flow in the passages of the turbine rotor and at the exit ends of the rotor blades are avoided. The turbine rotor blades at their exit ends are so directed that, at least behind the interior of the rotor, a substantially axial velocity results. The radially outer portions of the exit ends of the rotor blades may also have slightly bent surfaces. The angle relative to a plane perpendicular to the rotor axis at which the tip of the outlet end of each rotor blade is disposed may diifer from the angle relative to said plane at which the base of the outlet end of the blade is disposed so that. an absolute velocity is imparted to the gas adjacent the tip of the blade diilering in direction from the absolute velocity of the gas ,adjacent the base of the blade thereby creating a vortex in the gas ow leaving the rotor. The blades could be initially plane, disposed obliquely to the turbine axis. The plane surfaces can then be bent at their exit ends. The outlet ends of the rotor blades may be cut off obliquely to the turbine axis so that they lie substantially in a conical surface co-axial with the turbine axis. By this means the angle through which the ilow of gas is diverted from its radial inlet to the outer, more axial exit direction of the turbine is reduced. In a radial turbine according to the' invention the rotor may be combined with a diiusor through which the rotor discharges and which is adapted for effective conversion of velocity into pressure in the exit section of the gases,

whereby the gases leaving the rotor are directedk substantially axially through the diifusor.

Each rotor blade may lie mainly within a single plane extending from its entire inlet area to its lateral ends joining the disc-like body of the rotor or may have slightly bent surfaces toward the radially outer portions of the exit ends of the blades which bent surfaces produce a slightly tangentially directed velocity in the gases adjacent the surface of the diiusor creating a vortex in the gas flow in the diffusor. This measure is intended to obtain in the adjacent diffusor a. conversion of velocity into pressure as favourably and uniformly as possible and in addition to minimize separation of gas flow from the wall surfaces. The minimum internal diameter of the diffusor at its inlet end may be smaller than the diameter across the tips of the turbine blades at their outlet ends and the mini- -murn cross sectional area of the diifusor at its inlet end may approximate the aggregate cross sectional areas of the said passages at their outlet ends. The reason for this construction is to maintain as constant as possible the absolute velocity of the gas discharging from the turbine rotor at the inlet end of the dffusor for the purpose of avoiding energy losses due to vanishing of velocity resulting from the terminal thickness of the turbine blades.

Several embodiments of the invention inclusive of details thereof are illustrated, by way of example only, in the accompanying drawings, in which Figs. 1 to 6 represent a single stage gas turbine, as a first embodiment of the invention, the turbine being in driving engagement with a blower rotor and having four diierent gas supply conduits,

Fig. 1 being a section on the line I--I in Fig. 2;

Fig. 2 a. section on the line II--II in Fig. 1;

Fig. 3 a section on the line III--III in Fig. 2;

Fig. 4 a perspective view of the turbine rotor inclusive of the blading thereof;

Fig. 5 a view of a modified detail of Fig. 4, and

Fig. 6 a sectional view of a modied detail of Fig. 1.

Fig. 7 shows a side elevation partly in section on the line VII--VII in Fig. 8 of a. second em'- bodiment of the invention;

Fig. 8 is a sectional view on the line VIII-VIII in Fig. '7;

Fig. 9 is a sectional view-of the line DI-IX in Fig. 8;

Fig. 10 shows a modification of a detail of Fi 7;

igs. 11 and 12 each represent diagrammatically various velocities; and

Fig. 13 is a section on the line XIII-XIII in Fig. 1.

Fig. 1 shows a vradial turbine rotor I which is rotating in a bearing support 3 by means of a shaft 2. admission casing whereas refers to the nozzle carrier ring containing the inlet blades 6 and I5 (Figs. 2, 8 and 13) and 'I refers 'to a closure member which is provided with a cooling space 8 and is arranged between the gas inlet casing 4 andthe compressor collecting casing 9.

'I'he turbine rotor forms an integral piece having a disc-like wheel body I the ilat blades of which are, for example, worked out of the material of this body. These blades I 1, one of which is shown in elevation centrally of the wheel at I1, I8 (Fig. 1), have the characteristic feature that their surfaces project from the rotor disc I in oblique rel-ation to the axis of the rotor and that they extend radially across the full blade width at least at the outer circumference of the rotor disc, when seen in the direction of the rotor axis. At the bases I8 of the blades I'I, at

the .points where the latter are connected to thev wheel disc I, thickened blade portions are provided for reasons of strength. The bases of the blades, when seen transversely to rthe rotor axis, are curved towards the direction of this axis so as to divert the passages between the blades from the radial into the axial direction. i

In thus hollowing out the turbine rotor I in the axial direction toward the exit end 20, for forming these passages between the blades I'I, care is taken that relatively smooth. that is, gently curved contours 2| lare formed. When a diiusor 22 is arranged behind the turbine rotor, as shown in the examples illustrated in Figs'. 1, 6I 7 and 10, the direction of inclination of the rotor blades and the cross sections between the rotor blades are so designed that the gases leave the discharge edges 20 under a lower pressure than the discharge pressure at the end 23 of the diffusor 22, and at relatively higher Velocity, and then enter the rectilinearly conically widening diiusor 22. The design of the diiusor 22 is such that at the end 23 thereof the pressure of the gases increases substantially to the value of the discharge pressure in the exhaust pipe or to atmospheric pressure, if exhausting into the atmosphere takes place.

In order to provide for the conversion of velocity taking place in the diiusor 22 to be eflicient, a conically tapering guide piece 24 adjoining the hub of the turbine rotor 'I may be arranged in the interior of the diifusor 22. This guide piece 24 prevents the velocity of the gas discharging from the turbine rotor I from van- The-numeral 4 designates the turbine` in Fig. 6. In such a case, the gases discharging from the turbine rotor blading I'I are supplied to the diiusor 22 through an intervening pipe bend 25' which also may be provided with a guide piece, such as 26, having the eilect of preventing the velocity from being abruptly reduced.

In the center of Figs. 2 and 13 the construction of the turbine rotor blades I1 is shown in detail. Although the blades I'I forming the gas passages are generally flat and incline to the rotor axis, as mentioned above, the inlet end portions I9 of the' blades I1 adjoining the outer periphery of the rotor extend in radial direction.- The discharge end portions 20 of these blades I 'I also extend radially or are only slightly inclined to the radial direction. The inlet casing 4 of the turbine is integral with the diusor arrangement '22 (Fig. 1). Four supply conduits I0, II, I2 and I3 (see also Fig. 3) form an arrangement of crowded convolutions so that the outer diameter of the casing 4 is reduced to a minimum. The areas of ishing abruptly, at loss of energy on the inside free passage of the spiral entrance portions of the conduits I0, Il, I2 and I3 decrease to such an extent that uniformity of velocity is maintained up to the entry of all the tapering nozzles I4 and but a relatively slight diversion of the gases into the direction of admission is required to take place. Between each pair of the spiral inlet conduits I6, II, I2 and I3, one of four separating blades I5 (Figs. 2, 8 and 13) is provided, and in eachinterstice therebetween are arranged only two nozzle blades 6 which also extend in the tangential direction and which jointly ensure that the gases are admitted to the turbine rotor in the required direction and at the-appropriate gas velocity. Due to the tangential guiding eiect produced by the inlet conduits I0, I I, I2 and I3, that is, that of the separating blades I5 and the intervening blades 6, the iiow of gas undergoes diverting movements at large radii of curvature throughout. Consequently'the losses of energy suffered in advance of the-turbine rotor are only small. Fig. 2 further shows plainly the manner in which the supply conduits l0, Il, I2 and I3 are crowded into narrow convolutions up to their exit ends. At 22 and 24 in Fig. 1, the outer wall and the inner guide wall respectively of the diffusor are shown in cross section.

Fig. 3 exemplifies the manner in which vthe four separate supply conduits I0, Il, I2 and I3 are relatively arranged on the gas entrance side.

Fig. 4 being a perspective view of the turbine rotor I, clearly shows the radially directed entrance ends I9 and the approximately radially directed exit ends 20 of the turbine rotor blading I'I. From this illustration it will be plainly seen that the approximately plane iianks of the rotor blades extend obliquely to the turbine axis, and that the thickness of these blades increases particularly in the radial direction and toward the blade bases I8 at the turbine wheel disc.

,The second embodiment of the invention as shown in Fig. 7 comprises a gas turbine with only two inlet conduits I0' and II'. The numeral I1 refers to the turbine rotor blades having inlet ends I9 and exit ends 20'. These exit ends 20' are cut oi obliquely to the turbine axis (Fig. 7 sectional portion). It will be clearly seen that the innermost diameter of smallest length of thediffusor 2'2 is smaller than the extreme diameter of the outer exit ends v2li' of the turbine blades l1', commensurate with the Obliquity of said ends. The reason for this construction is to obtain at the inlet end of the diiusor 22" substantially the same absolute gaslvelocity as that existing at the discharge end 2II' of the turbine rotor I, for the purpose of avoiding energy losses due to abrupt reduction of velocity, This is accomplished by keeping down the cross section of free passage at the inlet end of the diiusor 22", at least to such a size as to correspond with the effective absolute gas discharge area of the turbine rotor blading considering the terminal thickness of blades. In this construction the exit ends 20' of the blades lie in a conical surface coaxial with the turbine axis. By this means the angle through which the flow of gas must be diverted from its inlet area I9' up to the outer exit area 20' 'of the turbine rotor I is reduced, compared with an execution according to Fig. 1. The losses caused by deflection of the gas iiow in the turbine blading are therefore decreased. When the velocity of the gas relative to the turbine blading is greater than its absolute velocity at the exit oi the turbine blading, the deflection of the gas ow beyond, that is, outside of the turbine blading, where the gases enter the diiusor, causes less energy losses.

In a construction as shown in Fig. 7 no gap losses arise in the discharging gas at the point of transitionfrom the turbine rotor I to the piece 24', in contrast to the construction shown in Fig. 1, due to the fact that no open gap extending transversely of the gas-stream exists between the turbine rotor and the diiusor.

In Fig. 8 as seen from the left hand side of Fig. 7, the form of the turbine rotor blades II' inclusive of their radially directed inlet ends I9 and their substantially radially extending exit ends 20' is Shown. 'The two supply conduits lilv and II' forming a crowded arrangement of con- 'ing in parallelism with the turbine axis.

Fig. l0 represents a modification of the construction of the inlet nozzles I4 and a corresponding form of the turbine rotor blading I1". The inlet direction of the nozzles I4 is -no longer radial, but, when seen transversely to the turbine axis, inclined at an acute angle to the axis of the turbine rotor I which corresponds to the direction of flow of 'gas at point I6 in this figure. Now since the turbine blade entrances have the same obliquity as the nozzles, this arrangement results in a reduced angle of diversion of the flow of gas during the passage of the gas through the turbine rotor I from the radial direction as shown in Figs. 1 and 'l into the axial direction. The direction of the hollow parts or buckets of the turbine rotor blading I1" must naturally then be in correspondence with the direction of gas aclmission, as shown in this figure. Fig. 11 represents the gas inlet velocity triangle at the blade entrance IB of the turbine, in which ci designates the absolute gas admission velocity, u1 the velocity of the circumference of the rotor, and w1 the relative gas admission velocity which ,is approximately radially directed in accordance with the present invention.

Fig. 12 represents the gas velocity diagrams at y sponding absolute gas velocity. The character un" represents the smaller circumferential velocity at the blade I 8, wz" the relative gas velocity at the last named point, and ca" the corresponding absolute gas velocity.

According to the invention. the inclinations of the rotor blades and the dimensions of the cross sectional areas between these blades are so chosen that, as illustrated in Fig. 12, at the exit end of the turbine rotor the relative gas velocities wa' and wz" are substantially equal to each other, and also the absolute velocities cz' and cz" are substantially equal to each other. Further in the interior of the diiusor according to the invention a substantially axially directed velocity ca" must result, and at the .outer diffusor circumference there may exist a slightly tangentially directed velocity c2 producing a vortex in the gas ilow. Both measures are intended to obtain in the diffusor 22 a conversion of velocity into pressure as favorable and uniform as possible and in addition little separation of gas from the wall surfaces even in a more widely ared and relatively shorter dilusor. For this purpose on the outer end the angle a2 of the blades must be chosen to be smaller than at the inner end in accordance with az". For obtaining the corresponding exit angles aa' andai" (see Fig. 12 and the description thereof) in an arrangement according to the present invention, the blade surfaces can be formed firstly of initially plane surfaces in conformity with the exit angle a2" at the blade base I8, then the outer ends are bent up or pressed into the desired different direction in accordance with the exit angle a2'. if requiredin hot state.

I claim,

l. A rotor for a radial turbine particularly adapted for use with hot gaseous motive fluids, consisting of a disc-like body presenting a plurality of blades successively spaced from each other to form the side Walls of a plurality of successive passages, the said body forming bottom walls for the said passages between adjacent blades, the passages being arranged to receive gas admitted substantially radially at the outer periphery of the rotor and to direct the gas inwardly toward the axis of the rotor, the bottom walls being curved from radial to axial directions as the gas ilows radially inwardly and then axially from the inlet to the `outlet ends of the passages, the inlet end of the bottom wall lying in a plane substantially perpendicular to the rotor axis and the outlet end of the bottom wall extending in a direction along the rotor axis, each blade extending obliquely to the rotor axis and each side of each blade lying substantially within a single plane.

2. A rotor for a radial turbine as defined in claim 1 in which the cross-sectional area of the outlet end of each passage and the inclination of the outlet ends of the blades produce relative gas velocities adjacent the base and adjacent the tip of 'the outlet end of each blade which are substantially equal to each other and also produce absolute gas velocities adjacent those points which are substantially equal to each other.

3. A rotor for a radial turbine particularly adapted for use with hot gaseous motive fluids, consisting of a disc-like body presenting a plurality of blades successively spaced from each other to form the side walls of a plurality of successive passages, the said body forming bottom walls for the said passages between adjacent blades, the passages being arranged to receive gas admitted substantially radially at the outer periphery of the rotor and to direct the gas inwardly toward the axis of the rotor, the bottom walls being curved from radial to axial directions as the gas flows radially inwardly and then axially from the inlet to the outlet ends of the passages, the inlet end of the bottom wall lying in a plane substantially perpendicular to the rotor axis and the outlet end of the bottom wall extending in a direction along the rotor axis, each blade extending obliquely to the rotor axis and each side of each blade lying mainly within a single plane extending from its entire inlet area to its lateral ends joining the disc-like body of the rotor and having slightly bent surfaces towards the radially. outer portions of the exit ends of the blades.

4. The rotor as deiined in claim 1 in which the angle, relative to a plane perpendicular to the rotor axis, at'which the tip of the outlet end of each blade is disposed diiers from the angle, relative to said plane, at which the base of the outlet end of the blade is disposed so that an absolute velocity is imparted tothe gas adjacent the tip of the blade differing in direction from the absolute velocity of the gas adjacent the base of the blade, thereby creating a vortex inthe gas iiow leaving the rotor.

. 5. The rotor as defined in claim 1 in which the outlet ends of the blades are cut off obliquely to the turbine axis so that they lie substantially in a conical surface co-axial with the turbine axis.

6. In a turbine particularly adapted for use with hot gaseous motive nuids, the combination of a rotor and a dilusor through which the rotor discharges, adapted for effective conversion of velocity into pressure in the exit gases, the rotor consisting of a disc-like body presenting a plurality of blades successively spaced from each other to form the side walls of a plurality of successive passages, the said body forming bottom walls for the said passages between adjacent blades, thepassages being arranged to receive gas admitted substantially radially at the outer periphery of the rotor and to direct the gas inwardly toward the axis of the rotor, the bottom walls ing obliquely to the rotor axis and each side of v each blade lying substantially within a single plane, whereby the gases leaving the rotor are directed substantially axially through the diiusor.

7. In a turbine particularly adapted for use with hot gaseous motive fluids, the combination `of a rotor and a diffusor through which the rotor discharges, adapted for effective conversion of velocity into pressure in the exit gases, the rotor consisting of a disc-like body presenting a plurality of blades successively spaced from each other to form the side walls of a plurality of successive passages, the said body forming bottom walls Cil for the said passages between adjacent blades, the passages being arranged to receive gas admitted substantially radially at the outer periphery of the rotor and to direct the gas inwardly toward vthe axis of the rotor, the bottom walls being curved from radial to axial directions as the gas flows radially inwardly and then axially from the inlet to thevoutlet ends of the passages, the inlet end of the bottom wall lying in a plane substantially perpendicular to the rotor axis and the outlet end of the bottom wall extending in a direction along the rotor axis, each blade extending obliquely to the rotor axis and each side of each blade lying mainly within a single plane extending from its entire inlet area to its lateral ends joining the disc-likebody of the rotor and having slightly bent surfaces towards the radially outer portions of the exit ends of the blades, which bent surfaces produce a slightly tangentially directed velocity in the gases adjacent the surface of the .diusor creating a vortex in the gas flow in the difusor.

8. In a turbine particularly adapted for use with hot gaseous motive fluids, the combination of a rotor and a diiusor through which the rotor discharges, adapted for eiective conversion of velocity into pressure in the exit gases, the rotor consisting of a disc-like body presenting a plurality of blades successively spaced from each other to form the side walls of a plurality of successive passages, the said body forming bottom walls for the said passages between adjacent blades, the passages being arranged to receive gas admitted substantially radially at the outer periphery of the rotor and to direct the gas inwardly toward the axis of the rotor, the bottom walls being curved from radial to axial directions as the gas ilows radially inwardly and then axially from the inlet to the outlet ends of the passages, the inlet end of the bottom wall lying in a plane substantially perpendicular to the rotor axis and the outlet end of the bottom wall extending in a direction along the rotor axis, each blade extending obliquely to the rotor axis-and each side of each blade lying substantially within a single plane, whereby the gases leaving the rotor are directed substantially axially through the diffusor, the minimum internal diameter of the diilusor at its inlet end being smaller than the diameter across the tips of lthe turbine blades at their outlet ends and the minimum cross sectional area of the diiusor at its inlet end approximating the aggregate cross sectional areas of the said passages at their outlet ends.

ALFRED BCHI;

REFERENCES CITED `The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,554,514 Moody Sept. 22, 1925 1,656,889 Moody Jan. 17, 1928 1,681,712 Taylor Aug. 21, 1928 2,384,265 Sollinger Sept. 4, 1945 2,390,506 Buchi Dec. 11, 1945 Certificate of Correction Patent No. 2,486,732 November 1, 1949 ALFRED BCHI It is hereby certied that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 3, for blade 18 read blade bases 18 line 33, before the Word then insert and; same line, after outer7 insert exit;

and that the said Letters Patent should be read With these corrections therein tha the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of February, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant Uommz'ssioner of Patents. 

